A diagram showing how concurrent sexual relationships foster the spread of HIV

Last night I watched the movieEntourage, which is based upon the HBO television program of the same name in which the exploits of a rising Hollywood star and his hometown "entourage" are detailed.

I didn't expect to find an important infectious disease topic in the movie but I am always on the look-out and--sort of fitting for a Hollywood star-focused movie--concurrent sexual networks came up when one character is put in a dilemma when his two concurrent sexual partners find out about each other and one of whom reveals she has a sexually transmitted infection which is assumed to be genital herpes.

Concurrent sexual networks are a pattern of sexual contacts that involve having more than one sexual partner at a time, as opposed to the serial monogamous relationships. While the number of total sexual partners over a specific period of time may be equivalent between an individual in serially monogamous relationships and one who is concurrent sexual relationships, the infectious disease implications are very different.

Concurrent sexual relationships dramatically increase the ability of a sexually transmitted infection to find new hosts, especially if the other partner also is involved in another concurrent sexual relationship. Amplification of spread is much more easily achieved in such a scenario.

It was study of the explosive nature of the HIV epidemic in Africa that really concretized the importance of concurrent sexual relationships and informed the "zero grazing" campaigns.

While a zero grazing policy may be anathema to the Hollywood elite depicted in the movie, it is fuel for the sexually transmitted infection fire.